The 'One Move Behind in Zumba Class' is just one new step from @FLOTUS and Fallon's Evolution of Mom Dancing 2

Jimmy Fallon and Michelle Obama have reunited for "The Evolution of Mom Dancing Part 2."

And here's a taste: "Oh My God, I Didn't Know You Were Coming Here!"

The first lady, who debuted the sketch with Fallon two years ago when he was the host of "Late Night," appeared on his "Tonight Show" on Thursday for a hefty helping of the "Shimmy Twist" and the "Knock Knock" in honor of FLOTUS' Let's Move health initiative and the Gimme Five Challenge.

Fallon kicked off the routine decked out in his same old campy mom uniform: a pink cardigan, khaki capris, white sneakers and a brown wig. Obama, 51, joined him in a similar pink cardigan but worked a slightly more updated look befitting the president's wife.

While the fun-and-frumpy moves started off basic enough, they evolved, and the duo introduced the lesser-known "Getting a Bag From Your Collection of Plastic Bags Under the Sink," the "I Can Still Do This Dance Because My Arms Are in Shape" and my favorite, the "One Move Behind in Zumba Class."

Jimmy Fallon, Michelle Obama

"The Evolution Of Mom Dancing" with Jimmy Fallon and Michelle Obama, from "Late Night with Jimmy Fallon"

"The Evolution Of Mom Dancing" with Jimmy Fallon and Michelle Obama, from "Late Night with Jimmy Fallon"